All invasive surgeries carry risk. A successful surgery is one which mitigates risk, potentially to the point of elimination, and minimizes post-operative care and recovery. Some surgeries carry little risk of negative post-operative consequences. For instance, wisdom teeth extraction is a type of minor, yet still invasive, surgery for which recovery time is a few hours to a few days, and for which there are very few risks associated with the surgery and the operation itself (ignoring risks associated with ancillary operative work, such as local or general anesthesia). Other surgeries, however, are routinely associated with risk and post-operative damage. For such surgeries, prospective patients must balance the damages against the benefits of the surgery.
Lower limb surgery, and hip arthroscopic or arthroplasty surgeries especially, fits within this latter type of surgeries. Extensive manipulation and re-orientation of a patient's leg is often required. During a hip arthroscopic procedure, the patient is placed in a supine or lateral position, and the femoral head is distracted 7-10 mm. This is necessary to gain access to the operative hip. In a hip arthroplasty, or hip replacement surgery, the femoral head is completely dislocated and fully removed from the hip socket. In either surgery, the surgeon must have clear access to the femoral head and the top of the femur for a significant amount of time. The leg must therefore be manipulated and maintained in a desired position for a prolonged period of time while the surgeon operates.
Hip arthroscopic surgery with patients in the supine position is exemplary of major lower limb procedures and is described primarily referred to herein as representative of other lower limb procedures. The patient is placed in traction on a specialized bed, operating table, or any other device that is used for traction (hereinafter, a “fracture bed”). Fracture beds typically have two independently-movable leg extensions fitted with aggressively-strapped restraints for the feet. The operative leg is pulled away from the hip distally by cranking the restrained foot away from the hip. Counter-traction is provided with use of a perineal post, covered by a pad, located between the patient's upper thighs and below the patient's perineum area. This is known as applying traction force. With traction force applied, the operative leg is additionally adducted against the perineal post which imparts a torqueing force that allows ultimately for distraction of the femoral head, thereby providing access to the hip socket. Clearly, a tremendous amount of force is placed on the leg and lower body. The perineal post is key to stabilizing a patient's body during traction. Fracture beds thus include the upstanding perineal post and often allow for placement of a pad over the perineal post.
During the procedure, both a large traction force and a large torqueing force are placed on the hip joint. These forces allow the surgeon to separate the femur from the hip socket, gain access to the femoral head, and repair the joint. These forces must be applied about the hip joint while bracing the rest of the patient's body. The post is the primary brace point for the whole body against these forces, and so opposing forces are located at the post. In resisting the traction and torqueing forces, the post places force on the perineal area, pelvis, pelvic area, inner thighs, and generally the region between and including the anus to the genitals. This force is typically applied continuously in arthroscopic hip surgery for two to three hours, and the traction force alone is generally 50 lbs of force.
Nerves, arteries, and veins in the perineal area are often damaged during hip arthroscopic surgery by these perineal post forces. Because the surgeon needs prolonged access to the femoral head, the force at the post is continuously applied for hours. During this time, the perineal area is compacted against the post, and soft tissue regions, nerves, nerve endings, and vascular pathways are essentially crushed. Traction and torque forces can cause temporary harm and potentially permanent damage to these areas. Patients can be left with pudendal nerve neuropraxia and lesions to the area of applied force. Neuropraxia of the ischial nerve is one of the primary post-operative symptoms observed. Other problems include impotency issues, urination difficulties, numbness, deep vein thrombosis, pulmonary embolisms, and infections. Nonetheless, most patients will choose to have the hip arthroscopic or arthroplasty surgery performed, sometimes forfeiting their previous sensory, sexual, and urinary abilities in doing so.
Attempts have been made to mitigate harms related to lower-limb procedures. Pads for the posts have been developed. Most are basic, such as cylindrical, heavily-foamed covers for placement over the rigid fracture bed post. Most have drawbacks, however. For example, many do not actually alleviate the impact on the perineum region, pudendal nerve, groin, and anus, or at least do not significantly reduce the incidence of post-operative trauma; rather, they still transfer the applied force to these areas. In fact, many can worsen the problem; when some pads compress, their cylindrical design has the effect of applying the entirety of the post forces onto a very small surface area. This greatly increases the risk of traction harm. Many pads create new problems; some pads roll or rotate, which pitches or moves the patient's body during surgery. Some pads tends to deform or collapse under the force and can actually trap and squeeze a patient's testicles during the procedure. The surgeon, if he or she becomes aware of such perioperative problems, may need to re-position the body, which is time-intensive can require scrubbing out and back in. In fact, much of the surgical time is consumed just by re-positioning the body and the necessary activities associated with it.
It is clear that an improved device for minimizing the harm of hip replacement and other lower limb surgery is needed.